1. Field of the Invention
The present invention concerns a process for the formation of a thin film of a porous metal oxynitride having a high surface area on the surface of an electrically conducting substrate. The metal chloride is dissolved in a volatile organic liquid, a substrate is coated with a film, the film is converted to the porous metal oxide which is then converted to the porous metal oxynitride. The thin layer metal oxynitride covered-substrate is useful for electrical energy storage as an electrode in a capacitor or battery configuration.
The present invention generally relates to an energy storage device, and more particularly to a bipolar double layer capacitor-type energy storage device, and to improved methods for manufacturing the same.
2. Description of the Related Art
Energy Storage Devices--There has been significant research over the years, relating to useful reliable electrical storage devices, such as a capacitor or a battery. Large energy storage capabilities are common for batteries; however, batteries also display low power densities. In contrast, electrolytic capacitors possess very high power densities and a limited energy density. Further, carbon based electrode double-layer capacitors have a large energy density; but, due to their high equivalent series resistance (ESR), have low power capabilities. It would therefore be highly desirable to have an electrical storage device that has both a high energy density and a high power density.
A review by B. E. Conway in J. Electrochem. Soc., vol. 138 (#6), p. 1539 (June 1991) discusses the transition from "supercapacitor" to "battery" in electrochemical energy storage, and identifies performance characteristics of various capacitor devices.
D. Craig, Canadian Patent No.1,196,683, in November 1985, discusses the usefulness of electric storage devices based on ceramic-oxide coated electrodes and pseudo-capacitance. However, attempts to utilize this disclosure have resulted in capacitors which have inconsistent electrical properties and which are often unreliable. These devices cannot be charged to 1.0 V per cell, and have large, unsatisfactory leakage currents. Furthermore, these devices have a very low cycle life. In addition, the disclosed packaging is inefficient.
M. Matroka and R. Hackbart, U.S. Pat. No. 5,121,288, discusses a capacitive power supply based on the Craig patent which is not enabling for the present invention. A capacitor configuration as a power supply for a radiotelephone is taught; however, no enabling disclosure for the capacitor is taught.
J. Kalenowsky, U.S. Pat. No. 5,063,340, discusses a capacitive power supply having a charge equalization circuit. This circuit allows a multicell capacitor to be charged without overcharging the individual cells. The present invention does not require a charge equalization circuit to fully charge a multicell stack configuration without overcharging an intermediate cell.
H. Lee, et al. in IEEE Transactions on Magnetics, Vol. 25 (#1), p.324 (January 1989), and G. Bullard, et al., in IEEE Transactions on Magnetics, Vol. 25 (#1) p. 102 (January 1989) discuss the pulse power characteristics of high-energy ceramic-oxide based double-layer capacitors. In this reference various performance characteristics are discussed, with no enabling discussion of the construction methodology. The present invention provides a more reliable device with more efficient packaging.
Carbon electrode based double-layer capacitors have been extensively developed based on the original work of Rightmire, U.S. Pat. No. 3,288,641. A. Yoshida et al., in IEEE Transactions on Components, Hybrids and Manufacturing Technology, Vol. CHMT-10, #1,P-100-103 (March 1987) discusses an electric double-layer capacitor composed of activated carbon fiber electrodes and a nonaqueous electrolyte. In addition, the packaging of this double-layer capacitor is revealed. This device is on the order of 0.4-1 cc in volume with an energy storage capability of around 1-10 J/cc.
T. Suzuki, et al., in NEC Research and Development, No. 82, pp. 118-123, July 1986, discloses improved self-discharge characteristics of the carbon electric double-layer capacitor with the use of porous separator materials on the order of 0.004 inches thick. An inherent problem of carbon based electrodes is the low conductivity of the material resulting in a low current density being delivered from these devices. A second difficulty is that the construction of multicell stacks is not done in a true bipolar electrode configuration. These difficulties result in inefficient packaging and lower energy and power density values.
Ultracapacitors provide one approach to meet the high power requirements for the advanced energy storage system for many uses, from cardiac pacemakers to cellular phones to the electric automobile. Until recently, the only packaged high power ultracapacitor material available for significant charge storage has been a mixed ruthenium and tantalum oxide (Z. W. Sun and K. C. Tsai, J. Electrochem. Soc. Ext. Abs., vol. 95-2, pp. 73-76 (1995) and R. Tong et al., U.S. Pat. No. 5,464,453 (1995)). Unfortunately, ruthenium and tantalum oxide are expensive.
Additional references of interest include, for example:
The state of solid state micro power sources is reviewed by S. Sekido in Solid State Ionics, vol. 9, 10, pp. 777-782 (1983).
M. Pham-Thi et al. in the Journal of Materials Science Letters, vol. 5, p. 415 (1986) discusses the percolation threshold and interface optimization in carbon based solid electrolyte double-layer capacitors.
Various disclosures discuss the fabrication of oxide coated electrodes and the application of these electrodes in the chlor-alkali industry for the electrochemical generation of chlorine. See for example: V. Hock, et al. U.S. Pat. No. 5,055,169 issued Oct. 8, 1991; H. Beer U.S. Pat. No. 4,052,271 issued Oct. 4, 1977; and A. Martinsons, et al. U.S. Pat. No. 3,562,008 issued Feb. 9, 1971. These electrodes, however, in general do not have the high surface areas required for an efficient double-layer capacitor electrode.
It would be useful to have a reliable long-term electrical storage device, and improved methods to produce the same. It would also be desirable to have an improved energy storage device with energy densities of at least 20-90 J/cc.
Packaging of Energy Storage Devices--As mentioned above, there has been significant research over the years regarding electrical storage devices of high energy and power density. The efficient packaging of the active materials, with minimum wasted volume, is important in reaching these goals. The space separating two electrodes in a capacitor or a battery is necessary to electrically insulate the two electrodes. However, for efficient packaging, this space or gap should be a minimum. It would therefore be highly desirable to have a method to create a space separator or gap that is substantially uniform and of small dimension (less than 5 mil (0.0127 cm).
A common way to maintain separation between electrodes in an electrical storage device with an electrolyte present (such as a battery or capacitor) is by use of an ion permeable electrically insulating porous membrane. This membrane is commonly placed between the electrodes and maintains the required space separation between the two electrodes. Porous separator material, such as paper or glass, is useful for this application and is used in aluminum electrolytic and double layer capacitors. However, for dimensions below 1 or 2 mil (0.00254 to 0.00508 cm) in separation, material handling is difficult and material strength of the capacitor is usually very low. In addition, the open cross-sectional areas typical of these porous membrane separators are on the order of 50-70%.
Polymeric ion permeable porous separators have been used in carbon double layer capacitors as discussed by Sanada et al. in IEEE, pp.224-230, 1982, and by Suzuki et al. in NEC Research and Development, No. 82, pp. 118-123, July 1986. These type of separators suffer from the problem of a small open area which leads to increased electrical resistance.
A method of using photoresist to fill voids of an electrically insulating layer to prevent electrical contact between two electrode layers for use as a solar cell is disclosed by J. Wilfried in U.S. Pat. No. 4,774,193, issued Sep. 27, 1988.
A process of creating an electrolytic capacitor with a thin spacer using a photosensitive polymer resin solution is disclosed by Maruyama et al in U.S. Pat. No. 4,764,181 issued Aug. 16, 1988. The use of solution application methods described with a porous double-layer capacitor electrode would result in the undesirable filling of the porous electrode.
A number of reports are found in the art to produce various metal nitrides having high surface area. Metal nitrides of particular interest include molybdenum nitride, titanium nitride or iron nitride.
Some additional specific references in this art include the following:
PCT/US93/08803, filed Sep. 17, 1993, Inventors: Tsai, K. C. et al., Int. Pub. No.: WO 94/07272, Int. Pub. Date: Mar 31, 1994.
PCT/US95/03985, filed Mar. 30, 1995, Inventors: Tsai, K. C. et al., Int. Pub. No.: WO 95/26833, Int. Pub. Date: Oct 12, 1995.
PCT/US95/15994, filed Dec. 11, 1995; Inventors: L. T. Thompson et al., Int. Pub. No. WO 96/19003, Int. Pub. Date: Jun. 20, 1996.
Robert R. Tong, et al., U.S. Pat. No.: 5,464,453, Issued: Nov. 7, 1995, U.S. Ser. No.: 947,294, Filed: Sep. 18, 1992, U.S. CI. 29/25.03.
Robert Tong et al., U.S. Pat. No.: 5,384,685, Issued: Jan. 24, 1995, U.S. Ser. No.: 947,414, Filed: Sep. 18, 1992, U.S. CI. 361/503.
Additional U.S. Patents of general interest include U.S. Pat. Nos. 4,515,763; 4,851,206; 5,062,025; 5,079,674; 4,327,400; and 5,185,679.
Molybdenum Nitride (Mo.sub.2 N, MoN)--Low cost, high surface area, and conductive molybdenum nitride is a potential candidate as an alternative material for a high charge storage capacitor. Many reports appear in the literature which describe the formation of molybdenum nitride as a powder having high surface area. A number are listed below. However, none of these references disclose the formation of an adherent film of high surface area molybdenum nitride having improved adhesion on a substrate on a surface. The reaction of powdered molybdenum oxide (MoO.sub.3) with ammonia (NH.sub.3) is described to produce .gamma.-molybdenum nitride (Mo.sub.2 N), which has a fcc structure with a surface area in excess 200 m.sup.2 /g (L. Volpe and M. Boudart, J. Solid State Chem., 59, 332 (1985)).
For molybdenum nitride production and testing, the following art is of interest:
D. Finello in "New Developments in Ultracapacitor Technology" reported at the Fourth International Seminar on Double Layer Capacitors and Similar Energy Storage Devices (Volume 4) Dec. 12-14, 1994, Deerfield Beach, Fla. reported a study of a molybdenum nitride sample. The molybdenum nitride was described as being prepared by treatment of the oxide film on the surface of a solid foil with ammonia at elevated temperatures. The results show that the nitride is marginally useful as a porous energy storage.
D. Finello in "Characterization of Molybdenum Nitride Electrodes" reported at the Fifth International Seminar on Double Layer Capacitors and Similar Energy Storage Devices, Dec. 4-6, 1995, Boca Raton, Fla. describes the comparison of molybdenum nitrides formed by heating the molybdenum oxide film on the surface of a substrate with ammonia. MoCl.sub.5 may be used as a starting material. The product Mo.sub.2 N is not pure and is contaminated with MoO.sub.2 and MoN.
M. Wixom in "Non-Oxide Ceramic Electrodes", disclosed at the Fifth International Seminar on Double Layer Capacitors and Similar Energy Storage Devices, Dec. 4-6, 1995, Boca Raton, Fla., Vol. 5 that certain metal nitride and metal carbide electrodes can be used for volumetric energy density and power density. Additional detail is not provided.
M. Goodwin in "PRI Ultracapacitors and Evaluation of Molybdenum Nitride" reported at the Fifth International Symposium on Double Layer Capacitors and Similar Energy Storage Devices, Dec. 4-6, 1995, Boca Raton, Fla., in general that molybdenum nitride may make a useful electrode. The production of such an electrode was not disclosed.
L. Volpe and Boudart M. "Compounds of molybdenum and tungsten with high specific surface area". Journal of Solid State Chemistry. vol.59, 332-347 (1985).
L. Volpe and Boudart M. "Ammonia synthesis on molybdenum nitride". J. Phys. Chem. vol.90, 4874-4877 (1986).
G. S. Ranhotra, Bell, A. T. and Reimer, J. A. "Catalysis over molybdenum carbides and nitrides II. Studies of CO hydrogenation and C.sub.2 H.sub.6 hydrogenolysis". Journal of Catalysis. vol. 108, 40-49 (1987).
G. S. Ranhotra, Haddix, G. W., Bell, A. T. and Reimer, J. A. "Catalysis over molybdenum carbides and nitrides I. Catalyst characterization". Journal of Catalysis. vol. 108, 24-39 (1987).
E. J. Markel and Van Zee, J. W. "Catalytic hydrodesulfuriza-tion by molybdenum nitride". Journal of Catalysis. vol. 126, 643-657 (1990).
C. H. Jaggers, Michaels, J. N. and Stacey, A. M. "Preparation of high-surface area transition-metal nitrides: MO.sub.2 N and MoN. Chemistry of Materials. vol. 2, 150-157 (1990).
J-G. Choi, Choi, D. and Thompson, L. T. "Preparation of molybdenum nitride thin films by N.sup.+ ion implantation".J. Mater. Res. vol. 7, 374-378 (1992).
L. T. Thompson, CoIling, C. W., Choi, D., Demczyk, B. G. and Choi, J-G. "Surface and catalytic properties of molybdenum nitrides". New Frontiers in Catalysis. 19-24 (1992).
Jeong-Gil Choi. "Temperature-programmed desorption of H.sub.2 from molybdenum nitride thin films". Applied Surface Science. vol. 78, 299-307 (1994).
R. S. Wise, and Markel, E. J. "Catalytic NH3-decomposition by topotactic molybdenum oxides and nitrides: Effect on temperature programmed .gamma.-MO.sub.2 N Synthesis". Journal of Catalysis. vol. 145, 335-343 (1994).
K. L. Roberts and Markel, E. J. "Generation of MO.sub.2 N nanoparticles from topotactic MO2N Crystallites". J. Phys. Chem. vol. 98, 4083-4086 (1994).
R. S. Wise and Markel, E. J. "Synthesis of high surface area molybdenum nitride in mixtures of nitrogen and hydrogen". Journal of Catalysis. vol. 145, 344-355 (1994).
J-G. Choi, Curl, R. L. and Thompson, L. T. "Molybdenum nitride catalysts". Journal of Catalysis. vol. 146, 218-227 (1994).
B. G. Demczyk, Choi, J-G and Thompson, L. T. "Surface structure and composition of high-surface-area molybdenum nitrides". Applied Surface Science. vol. 78, 63-69 (1994).
E. P. Donovan and Hubler, G. K. "Ion-beam-assisted deposition of molybdenum nitride films." Surface and Coatings Technology. vol. 66, 499-504 (1994).
C. W. Coiling and Thompson, L. T. "The structure and function of supported molybdenum nitride hydrodenitrogenation catalysts". Journal of Catalysis. vol. 146, 193-203 (1994).
C. H. Jaggers. "The preparation and characterization of high surface area transition metal nitrides". U.M.I. Dissertation Services. (1994).
M. S. Mudholkar and Thompson L. T. "Control of composition and structure for molybdenum nitride films synthesized using ion beam assisted deposition". J. Appl Phys. vol. 77, 5138-5143 (1995).
H. Joon Lee, Choi, J-G, Coiling, C. W., Mudholkar, M. S. and Thompson, L. T. "Temperature-programmed desorption and decomposition of NH.sub.3 over molybdenum nitride films". Applied Surface Science. vol. 89, 121-130 (1995).
Titanium Nitride (TiN)--Titanium nitride has a number of uses in the art. It is used to strengthen surfaces as a coating, as semiconductor layer and as electrode materials in electrical applications.
Some references of interest concerning titanium nitride include:
S. R. Kurts and Gordon, R. G. "Chemical vapor deposition of titanium nitride at low temperatures". Thin Solid Films, vol. 140, 277-290 (1986).
P. Mehta, Singh, A. K. and Kingon, A. I. "Nonthermal microwave plasma synthesis of crystalline titanium oxide & titanium nitride nanoparticles". Mat. Res. Soc. Symp. Proc. vol. 249, 153-158 (1992).
E. O. Travis and Fiordalice, R. W. "Manufacturing aspects of low pressure chemical-vapor-deposited TiN barrier layers". Thin Solid Films. vol. 236, 325-329 (1993).
Y. W. Bae, Lee, W. Y., Besmann, T. M., Blau, P. J. and Riester, L. "Synthesis and selected micro-mechanical properties of titanium nitride thin films by the pyrolysis of tetrakis titanium in ammonia". Mat. Res. Soc. Symp. Proc. vol. 363, 245-250 (1995).
H. Rode, and Hlavacek, V. "Detailed kinetics of titanium nitride synthesis". AlchE Journal. vol. 41, 377-388 (1995).
K-T. Rie, Gebauer, A., Wohle, J., Tonshoff, H. K. and Blawit, C. "Synthesis of TiN/TiCN/TiC layer systems on steel and cermet substrates by PACVD". Surface and Coating Technology. vol. 74-75, 375-381 (1995).
J. N. Musher, and Gordon, R. G. "Atmospheric pressure chemical vapor deposition of titanium nitride from tetrakis (diethylamido) titanium and ammonia". J. Electrochem. Soc. 143, 736-744 (1996).
In these applications, titanium oxide is used to produce the titanium nitride. The surface area is usually low and the electrical storage capacities are marginal.
Iron Nitride (FeN)--Iron nitride is described in few references.
For iron nitride production, the following art is of general interest:
A. Tasaki, Tagawa, K., Kita, E., Harada, S. and Kusunose, T. "Recording tapes using iron nitride fine powder". IEEE Transactions on Magnetics. vol. MAG-17, 3026-3031 (1981).
K. Tagawa, Kita E. and Tasaki, A. "Synthesis of fine Fe.sub.4 N powder and its magnetic characteristics". vol. 21, 1596-1598 (1982).
M. Kopcewicz, Jagielski, J., Gawlik, G. and Grabias, A. "Role of alloying elements in the stability of nitrides in nitrogen-implanted .alpha.-Fe". J. Appl. Phys. vol. 78, 1312-1321 (1995).
D. C. Sun, Lin, C., Jiang, E. Y. and Wu, S. W. "Multiphase iron nitride gradient films". Thin Solid Films. vol. 260, 1-3 (1995).
K. H. Jack. "The synthesis and characterization of bulk .alpha."-Fe.sub.16 N.sub.2 ". Journal of Alloys and Compounds. vol. 222, 160-166 (1995).
T. Chuijo, Hiroe, K., Matsumura, Y., Uchida, H. and Uchida, H. H. "Reactivity of N.sub.2 with Fe in FeN.sub.x formation by activated reactive evaporation process". Journal of Alloys and Compounds. vol. 222, 193-196 (1995).
F. Malengreau, Hautier, V., Vermeersch, M., Sporken, R. and Caudano, R. "Chemical interactions at the interface between aluminum nitride and iron oxide determined by XPS". Surface Science, vol. 330, 75-85 (1995).
None of these is art or in any configuration teaches or suggests the present invention.
Additional references of general interest include U.S. Pat. Nos, 3,718,551; 4,816,356; 4,052,271; 5,055,169; 5,062,025; 5,085,955; 5,141,828; and 5,268,006.
The metal oxynitrides have been studied, usually for use as a dense coating to provide chemical and physical resistance to surfaces.
Titanium nitride (TiN) has been studied extensively because of its many useful applications. It is already used as a wear-resistant coating on tools, as a gold substitute for decorative coatings and for thin film resistors. Its metallic conductivity and refractory stability make it the material of choice for diffusion barrier in microelectronics applications. S. Kurtz et al. in Thin Solid Films vol. 140, p. 277 (1986) measured 3 .mu.m TiN film that had 8.5 Moh's hardness scale, on which diamond is 10. It has the resistivity of 55 .mu..OMEGA. cm. Most of TiN thin films are produced by chemical vapor deposition (see, for example J. N. Musher et al. J. Electrochem Soc., vol. 143, p. 277 (1996), E. O. Travis, et al., Thin Solid Films, vol. 236, p. 325 (1993) and K.-T. Rie, et al., Surface and Coating Tech., vol. 74-75, p. 375 (1995)):
______________________________________ 2TiCl.sub.4 + N.sub.2 + H.sub.2 .fwdarw.2TiN + 8HCl 900-1200.degree. C. 6TiCl.sub.4 + 8NH.sub.3 .fwdarw.6TiN + 24HCl + N.sub.2 500.degree. ______________________________________ C.
Titanium oxynitride (TiNO) is a stable intermediate chemical product between titanium oxide and titanium nitride. These thin films of TiNO formed by sputtering are used as an anti-reflection coating (T. R. Pampalone, et al., J. Electrochem Soc., vol. 136, p. 1181 (1989)) and/or a diffusion barrier (N. Kumar. et al. Thin Solid Films, vol. 153, p. 287 (1987)). Only gas nitriding of titanium dioxide (TiO.sub.2) produces high surface area titanium oxynitride ((C. H. Shin, et al., Journal Solid State Chemistry, vol. 95, p. 145 (1991)). H. Teraoka, et al., in Japanese Patent 89-60729 describe that the titanium oxynitride is obtained by the reduction of TiO.sub.2 in nitrogen atmosphere.
Additional references for TiNO include:
C. H. Shin, et al., Journal of Solid State Chemistry, vol. 95, 145-155 (1991) disclose the preparation and characterization of titanium oxynitride having high specific surface area.
R. Marchand, et al., U.S. Pat. No. 4,964,016 disclose multi-layer ceramic capacitors having as the conductive elements therein, layers of perovskites containing oxygen and oxygen. However, these perovskite metal (1) metal (2) oxygen nitrogen structure compounds still have low conductivity. No capacitance data has been disclosed.
K. Kamiya, et al. in the Journal of Materials Sciences, vol. 22, p. 937-941 (1987) disclose the nitridation of TiO.sub.2 fibers prepared by the sol-gel method.
In view of the above, it would be very useful to have one or more methods to produce a reliable small space separation between electrodes in electrical storage devices with a large open cross-sectional area. The present provides these methods.
The present invention provides a process to produce a lower cost, adhering layer of porous high surface area metal oxynitride on a metal sheet (foil) substrate.